Tobacco use is the major preventable cause of cancer and disease burden in the U.S. While effective treatments exist, innovative means of efficient delivery are needed to accelerate reduction in smoking prevalence. Telephone counseling and tailored self-change programs have an evidence-base of efficacy and the capability to make an impact on population prevalence. There is a growing movement to provide comprehensive tobacco control services, both through telephone quit lines and tailored self-change via the Internet. Scientists, policy makers and the public need to know if these programs work, for whom, by what mechanisms, and at what cost. There are no rigorous evaluations of the efficacy of Internet-driven cessation services or of combined telephone and Internet treatment At the same time, Internet-based programs are already available to the public and are being used at a very high volume without any evidence that they are effective. This study aims to extend existing theory and application by comparing the efficacy of a popular, full service, Internet intervention (Premium Internet) alone or in conjunction with proactive telephone counseling (Premium Internet plus Telephone) against a standard Internet control (Basic Interact). This study will recruit motivated smokers (N=2,055) who use an Internet search engine to find smoking cessation programs. A subset will be directed to a Web page that will describe the study and enrollment procedures. Using a 3-condition randomized design with repeated measures at baseline, 3, 6, 12, and 18-months post-randomization, consented smokers will be assigned to: 1) Basic Internet; 2) Premium Internet; and 3) Premium Internet plus Proactive Telephone Counseling. The hypotheses tested are that Premium Interact plus Telephone will outperform Premium Internet alone and both will outperform Basic Internet on 7-day point prevalence abstinence measured at 12 months post-randomization (6-months post treatment). Cost-effectiveness will also be examined along with exploratory analyses of theory-driven hypotheses about the mediators and moderators of outcome (e.g., gender, amount and frequency of service use, type of content used, and behavior change variables including self-efficacy, social support, and motivation). Market demand and State health departments are stimulating delivery of Interact and telephone cessation services. There is an urgent need for science to fill the gap and evaluate their efficacy. If effective, such treatments can be widely disseminated and can make a significant impact on population health.